Absorbent pad structure, diaper construction utilizing same and methods of manufacture thereof

ABSTRACT

Absorbent pad made of air-laid fiberized or disintegrated pulp lap dry embossed to provide a bilaterally staggered pattern such as a close packed hexagonal pattern of low density tufts surrounded and separated by bilaterally extending non-linear and preferably sinuous regions of higher density to provide high softness impression together with high moisture wicking and transport and high surface dryness impression, methods of manufacture thereof by patterned densification as by compression in a calender stack between a patterned roll and a generally smooth back up roll, and diapers incorporating such pads between a top sheet and a back sheet.

United States Patent Wehrmeyer et a1.

ABSORBENT PAD STRUCTURE, DIAPER CONSTRUCTION UTILIZING SAME AND METHODSOF MANUFACTURE THEREOF US. Cl 128/287; 128/290 W; 128/284 Int. Cl A61F13/16; A61L 15/00 Field of Search 128/290 W, 284, 217, 287,

[451 Sept. 30, 1975 3.707.430 12/1972 Costanza et a1. 128/284 X3,721.242 3/1973 Krusko 3,812,001 5/1974 Ryan 128/284 57 ABSTRACTAbsorbent pad made of air-laid fiberized or disintegrated pulp lap dryembossed to provide a bilaterally staggered pattern such as a closepacked hexagonal pattern of low density tufts surrounded and separatedby bilaterally extending non-linear and preferably sinuous regions ofhigher density to provide high softness impression together with highmoisture wicking and transport and high surface dryness impression,methods of manufacture thereof by patterned densification as bycompression in a calender stack between a pat terned roll and agenerally smooth back up roll, and diapers incorporating such padsbetween a top sheet and a back sheet.

9 Claims, 3 Drawing Figures [56] References Cited UNlTED STATES PATENTS3,053,252 9/1962 Wolf 128/156 3.430.629 3/1969 Murphy 128/284 3,468,3119/1969 Gallagher 128/296 3.528.421 9/1970 Vaillancourt 128/284 US.Patent Sept. 30,1975

Fig. 1

Fig. 2

FIELD OF THE INVENTION This invention relates generally to disposableabsorbent pad structures.

DESCRIPTION OF THE PRIOR ART Absorbent pads fabricated of air-laidfiberized pulp lap and disposable diapers utilizing such pads are knownin the prior art. Such air-laid structures may be formed on a papertissue and an example of fiberizing ordisintegrating pulp lap andfelting thereof for manufacture of such a product is disclosed, forexample, in prior U.S. Pat. Nos. 3,519,211 to Sakulich, et ano and3,750,962 to Morgan, Jr., and ,co-pending application, Ser. No. 182,795,filed Sept. 22, 1971, by Kenneth B. Buell, now Pat. No. 3,825,194 andassigned to the assignee of this application. The disclosure of theaforesaid patents and application Ser. No. 182,795 are herebyincorporated herein, by reference, as fully and completely as ifphysically reproduced hereat and throughout this application the termfiberized and disintegrated pulp lap and air-laid pads and webs areintended to refer to a product such as that formed in accordance withsaid patents and application.

It has also been previously suggested to fully enclose such an air-laidfelt pad or bat within a tissue envelope to aid in supporting the feltduring processing, including converting, and to aid in preventingdisintegration thereof during use. See, e.g., Kalwaites U.S. Pat. No.3,444,859; Schutte U.S. Pat. No. 3,741,212; Costanza et al. U.S. Pat.No. 3,769,978.

It has also been recognized that increased wicking and fluid transfer ortransport within such a structure may be accomplished by densifying orcompressing the structure to provide an increased density thereof assuggested in, e.g., Duncan U.S. Pat. No. 3,592,194; Krusko, U.S. Pat.No. 3,721,242; and DeKnight U.S. Pat. No. 3,769,978. It has even beensuggested that a one directional generally sinuous pattern of compressednarrow strips may produce enhanced distribution of moisture in such astructure longitudinally along such strips. However, such narrowcompressed strips have also been recognized as barriers reducingtransverse moisture transport and also results in a stiffer and lesssoft product and have been formed by processing including wetting of thepad, and thereby changing the structure from a fully dry air-laidproduct. See, e.g., Morin U.S. Pat. No. 2,788,003. Further, it has beensuggested that compressing a pad of the general type referred to aboveso as to decrease the thickness thereof and increase the bulk density,not only creates increased wicking but, in addition, may produceincreased flexibility. See, e.g., Gobbo, Sr. et a1. U.S. Pat. No.3,065,751. However, the mere increase in flexibility does notnecessarily result in increased softness and what the prior art hasapparently not recognized, is that softness and flexibility are not thesame and, in fact, that structures exhibiting high flexibility mayprovide a very low softness impression to a user. Moreover, the priorart has also apparently not recognized that subjective surface drynessimpressions are not necessarily consistent with objective tests forsurface dryness and, in fact, subjective surface dryness impressions maybe 2 diametrically opposite objective surface dryness test results.

OBJECTS OF THE INVENTION Bearing in mind the foregoing, it is a primaryobject of the present invention to provide a novel and improvedabsorbent pad structure.

Another primary object of the present invention, in addition to theforegoing object, is to provide such novel and improved absorbent padstructures having optimized fluid wicking capabilities as well assurface dryness and softness impressions.

Yet another primary object of the present invention, in addition to eachof the foregoing objects, is the provision of such a novel and improvedabsorbent pad structures particularly constituted for use in adisposable diaper construction and disposable diaper structures'fabricated thereof.

Still another primary object of the present invention, in addition toeach of the foregoing objects, is the provision of novel methods ofmanufacture of such absor-. bent pad and diaper structures.

Yet still another primary object of the present invention, in additionto each of the foregoing objects, is the provision of a novel absorbentpad fabricated of air-laid defibered pulp lap, preferably within atissue envelope, subjected to dry pattern densification, as by patternedcompression, to provide a bilaterally extending stag gered pattern oflow density tufts surrounded by bilaterally extending non-linear andpreferably sinuously extending regions of increased density particularlysuitable for use in diapers and diaper-like structures and exhibitingenhanced fluid wicking characteristics, moisture retention capability,high surface dryness and high subjective surface dryness and softnessimpressions.

A yet further primary object of the present invention, in addition tothe foregoing objects, is the provision of novel methods of subjectingair-laid webs or pads of fiberized pulp lap to patterned densificationsby patterned compression from one side thereof to provide a tuftedstructure having a higher tuft height on said one side than on theother.

A yet still further primary object, in addition to the foregoingobjects, is the provision of improved diapers and diaper like structuresutilizing the improved absorbent pad structures of the present inventionand utilizing such pad structures with the higher tufted side facing thetop sheet for disposition facing'the childs skin in use to providemaximum lofting of the densified regions away from the child s skin aswell as providing the best look and feel to the outside facing surface.

The invention resides in the combination, construction, arrangement anddisposition of the various component parts and elements incorporated inimproved absorbent pad and diaper structures constructed in accordancewith the principals of this invention and the methods of manufacture inaccordance with the principals of this invention. The present inventionwill be better understood and objects and important features other thanthose specifically enumerated above will become apparent whenconsideration is given to the fol-.

lowing details and description, which when taken in conjunction with theannexed drawing describes, discloses, illustrates, and shows a preferredembodiment or modification of the present invention and what ispresently considered and believed to be the best mode of practicing theprincipals thereof. Other embodiments and modifications may be suggestedto those having the benefit of the teachings herein, and such otherembodiments of modifications are intended to be reserved especially asthey fall within the scope and spirit of the subjoined claims.

SUMMARY OF THE INVENTION In accordance with the present invention, thereis provided an improved absorbent pad structure and a diaper structureutilizing the same fabricated of air-laid disintegrated cellulose pulplap contained within a tissue envelope and dry embossed to provide astaggered pattern of low density tufts separated and surrounded bybilaterally extending sinuous regions of higher density providing anabsorbent pad having high fluid capacity, enhanced wicking, enhancedsurface dryness and exhibiting enhanced surface dryness and softnessimpression.

In accordance with the present invention, there is provided absorbentpad structure combining an enhanced softness impression with enhancedwicking and moisture transport capabilities to provide enhanced surfacedryness impression comprising, in combination, an air laid-pad ofdisintegrated cellulose pulp lap contained within a paper tissueenvelope providing structural integrity thereto, said pad being patterndensified to define bilaterally staggered spaced apart tufts formed byundensified regions of low density surrounded by and separated by abilaterally extending pattern of densified intersecting non-linearhigher density regions, said densified regions comprising betweenapproximately and 50 percent of the area of said pad.

DESCRIPTION OF THE DRAWING While the specification concludes with claimsparticularly pointing out and distinctly claiming the subject matterwhich is regarded as forming the present invention, it is believed thatthe invention will be better understood from the following descriptionwhich, taken in conjunction with the annexed drawing, describes,discloses, illustrates and shows a preferred embodiment or modificationof the present invention and wherein:

FIG. 1 is a plan view, partially broken away, illustrating a disposablediaper having a pattern densified and tufted absorbent air-laid pad inaccordance withthe present invention;

FIG. 2 is an enlarged cross sectional illustration taken along line 2-2of FIG. 1;

FIG. 3 is a cross sectional illustration diagrammatically illustrating amethod of manufacture of the improved absorbent pad of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawing,there is shown and il lustrated in FIGS. 1 and 2 an improved diaperstructure constructed in accordance with the principals of the presentinvention designated generally by the reference character 10.

The diaper as shown in the drawing can be formed, in general, inaccordance with the teachings of U.S. Pat. Re. No. 26,151, issued to R.C. Duncan et al., on Jan. 31, 1967, and the entire disclosure thereof ishereby incorporated herein by reference as fully and completely as ifphysically reproduced hereat.

The diaper 24 comprises an improved absorbent pad constructed inaccordance with the principals of the present invention and designatedgenerally by reference character 12. The pad 12 may be covered by asuperposed top sheet 14 which is preferably moisture pervious and whichmay provide a barrier between the improved absorbent pad 12 and a babysskin. The absorbent pad 12 may be backed by a back sheet 16 which ispreferably moisture impervious and is larger, at least in width, thanthe absorbent pad 12 to provide side flaps 18 which are folded over andonto the top surface of the top sheet 14 so that the side flaps 18 ofthe back sheet 16 overlie the lateral marginal area of the top surfaceof the top sheet 14 and the absorbent pad 12 there beneath. The backsheet 16 may also be larger in length than the absorbent pad 12 and thetop sheet 14 to provide end flaps 20 which are folded over and onto thetop surface of the top sheet 14 so that the end flaps 20 overlie thelongitudinal marginal area of the top surface of the top sheet 14 andunderlying absorbent pad 12. Hence, the absorbent pad 12 is fullycontained within an envelope defined by the top sheet 14 and back sheet16. The side flaps l8 and the end flaps 20 may be secured together atthe corners and to the underlying top sheet 14 and to the edge portionsof the pad 12 in any convenient manner, as by heat sealing, adhesivebonding, or like.

It is to be emphasized that although the absorbent pad 12 has beendescribed, disclosed, illustrated, and shown as being bound on both thesides and ends by the side flaps l8 and end flaps 20, respectively, sothat the absorbent pad 12 is fully contained within the envelope definedby the top sheet 14 and the back sheet 16, two of such flaps, andparticularly the end flaps 20 may be eliminated while yet enablingretention of the absorbent pad 12 between the top sheet 14 and the backsheet 16. More particularly, the absorbent pad 12 may be bonded toeither or both the top sheet 14 and the back sheet 16, as by, forexample and without limitation, heat sealing, adhesive bonding, pressurebonding, or the like.

Further, while the present invention is particularly described,disclosed, illustrated and shown herein as applied to a diaper, it is tobe expressly understood that the present invention is not limited to useagainst a baby for the absorption of urine, and the like, but may beutilized for many other related bandage and bandage like applications,including, by way of example only and without limitation, surgicaldressings, incontinence pads, sanitary napkins, and the like.

The side flaps l8, and the end flaps 20 when provided, should have aminimum width of about inch and preferably about 5 inch. The back sheet16 preferably is a flexible waterproof web, e.g., a 0.001 inch thick,low density, pattern embossed, opaque polyethylene web.

The top sheet 14 may be either hydrophobic or hydrophilic and may befabricated of a tissue paper made by a conventional water-laid process,subsequently creped; an air-laid tissue, a continuous filament nonwovenweb, a micro-porous film, or the like, and may be treated withwet-strength and/or bonding resins as will be apparent to those skilledin the art.

The improved absorbent pad 12 comprises a mat, pad, web, or bat 22 ofair-laid disintegrated pulp lap formed, for example, in accordance withthe teachings of Sakulich et al. U.S. Pat. No. 3,519,211; Morgan, .11.

U.S. Pat. No. 3,750,962; and co-pending Buell Application Ser. No.182,795 filed Sept. 22, 1971 and assigned to the assignee of the instantapplication. The mat or bat 22 may be contained between a pair of tissuelayers 24 and 26 superposed and subjacent thereto respectively.

The disclosures of the aforesaid patents are hereby expresslyincorporated herein by reference as fully and completely as if fully setforth hereat.

In addition to sheer absorptive capacity, two desirable attributes of adisposable diaper and of an absorptive pad for use therein are surfacedryness and softness. Air-felt density is one of the major factorscontrolling these attributes. The favorable density ranges are, however,different for the two attributes. Typically, low density favors a goodsoftness impression while presenting a poor skin dryness impression.Alternatively, high density favors a good skin dryness impression whileproviding a poor softness impression.

In other words, typically low density favors a good softness/flexibilityimpression while high density favors a good wicking/skin drynessimpression.

In accordance with the present invention, a pattern dry densification ofthe pad 12 (including both the fiber mat or bat 22 and the envelopetissues 24 and 26) is performed to provide a bilateral staggered patternof tufts 28 of substantially undensified, i.e., low density regionsseparated and surrounded by a generally nonlinear bilaterally extendingpattern of densified regions 30 of higher density so that the resultantabsorbent pad structure exhibits both good skin dryness and goodsoftness impression.

The high density regions 30 which, as heretofore pointed out, arebilaterally extensive provide good wicking and fluid transportthroughout the pad 12. Good wicking allows the moisture to be spreadmore evenly throughout the absorbent material and aids in attaining goodskin dryness.

The low density regions or turfts 28 provide a good softness impressionas well as providing regions having high liquid absorptive capacityspaced throughout the pad, providing a good skin dryness impression and,being of substantial height and resilience, tend to raise or loft thehigh density, wetter feeling regions from the babys skin.

Previously suggested schemes for compressing of air felts or pads toprovide sufficient high density area to offer good wicking and skindryness are stiff and boardy, while uncompressed pads which offerflexibility and softness do not provide sufficiently high density toprovide significant wicking and skin dryness. As has been pointed outhereinabove, it has been previously suggested to provide some localizedcompression of small portions of absorbent pads. However, such localizedcompression has been performed, usually together with the application ofwater or other liquid, either immediately prior to or during suchcompression, and such localized compression has been applied to only asmall percentage of the pad and primarily for bonding of the pad fibersor layers together. Moreover, such compressions, done wet or with theaddition of moisture, even if done at staggered location, adverselyaffects the softness of the pad. Furthermore, if such compression iseffected along linear strips, as has been previously suggested forincreasing wicking and fluid transport in the direction of thecompressed strips, the adverse effect of such compressed strips on theoverall softness of the pad is especially consequential, and althoughWicking and liquid transport parallel such compressed strips may beimproved thereby, such stripes actually inhibit fluid transport in thetransverse direction and act as barriers to wicking and fluid transportperpendicular thereto. The densification pattern of the presentinvention, however, offers sufficient high density area for good wickingand skin dryness while re maining soft and flexible. In accordance withthe present invention, the high density areas are basically nonlinearand, in fact, preferably extend sinuously bilaterally of the pad 12 soas to maintain flexibility which appears to be a major factor in overallsoftness impression.

Densification patterns providing densification of approximately twentyto fifty percent of the total area appear to be preferable, althoughsomewhat lower and higher percentages may provide acceptable, althoughnot optimum results. Below ten percent area densification, however,insufficient wicking occurs and above approximately seventy percentdensification, the densification pattern becomes inconsistent, anddifficult to maintain and unsatisfactory softness impressions result.

In accordance with the present invention, and with reference now moreparticularly to FIG. 3, the patterned densification of the air-felt orabsorbent pad 12 may be obtained by densifying the air-felt pad with,for example, a two roll calender stack 32 in which the pad or air-felt12 is compressed between a patterned roll 34 which has been debossedwith pcokets 36 defining the design pattern and a smooth backup roll 38cooperating therewith. The density in the high density region 30 may becontrolled by the pressure and separation between the patterned roll 34and the smooth backup roll 38. The density in the low density regions ortufts 28 may be controlled by either passing the air-felt or pad 12through a calender stack designated generally by the reference character40, comprising smooth surfaced pressure and backup rolls 42 and 44,respectively prior to passage between the rolls 34 and 38 or bycontrolling the depth of the debossed regions or pockets 36 in thepattern roll 34 corresponding to the low density regions or tufts 28.

Preferably, the pattern of tufts is staggered so that no straight linescan be extended across the densified region 30 which extends for anysubstantial distance in any direction. In other words, preferably thetufts or low density region 28 are of sufficient diameter and spacingthat, in any direction, their edges extend past one another. Further,the tufts should be of sufficient size to maintain their integrity,i.e., approximately inch to inch diameter with the preferable size beingapproximately 9/16 inch in diameter.

In practice, however, it has been found acceptable to define thedensification pattern to position the low density, undensified regionsor tufts 28 in a close packed regular hexagonal arrangement as shown inFIG. 1 even if, as shown, extremely narrow linear regions may exist,i.e., as designated by the center lines a, b, and c in FIG. 1 and asshown in emphasized form and designated 46 in FIG. 2 withoutsubstantially adversely affecting the softness impression, provided thatsuch linear regions are very narrow so as to constitute only a smallpercentage of the total area of the pad 12 and the generally sinuouslybilaterally extending pattern of densification.

It is also to be emphasized that, as used herein, the term bilateral orbilaterally is used and intended to mean extending in or having vectorsextending in at least two directions, and not limited to only twodirections. Hence, within the meaning hereof, the generally hexagonalpattern of FIG. 1 having lines of direction A, B, and C is a bilaterallyextending one, having lines of definition extending both generallytowards the ends (i.e., line A, as well as B and C) of the diaper andgenerally towards the sides (i.e., lines B and C) thereof.

The term tuft as used herein is intended to cover and define a region oflow density having substantial area projecting from the surroundinghighdensity region a significant amount and possessing substantialresilience and height. Hence, tufts of the present invention may havediameters on the order of to /4 inch or more, having a thickness 2-3times the thickness of the densified region.

EXAMPLE 1 To substantiate the surface dryness qualities of the presentinvention, a test was run, the object of which was to compare thesubjective surface dryness of diapers incorporating the same averagebasis weight and the same average density air-felt pads, differing onlyin that one sample was of generally uniform density while the other hadbeen subjected to pattern densification in accordance with the presentinvention. Sample L was a disposable diaper incorporating an air-feltpad having a generally uniform density of approximately 0.14 grams percubic centimeter and a generally uniform thickness of approximately0.085 inches. Sample N was a similar disposable diaper using a similarair-felt pad having an average density of approximately 0.14 grams percubic centimeter but which had been subjected to pattern densificationover approximately 50 percent of the area to provide generally circulartufts arranged in a close packed hexagonal staggered pattern of the typeshown in FIG. 1 covering approximately 50 percent of the area and havinga diameter of approximately 9/16 inches and an overall tuft height ofapproximately 0.150 inches. The densified regions extended bilaterallysinuously around and between the undensified tufts and had beendensified to a thickness of approximately 0.50-0.60 inches. Thedensified regions accordingly had a density of approximately 0.20 gramsper cubic centimeter. The samples were laid flat and each was wet with 114 cubic centimeters of a one percent saline solution adjusted to have asurface tension of 45 dynes. The test solution was applied generally tothe center of each sample and allowing the sample approximately 30minutes in which to absorb the water. Except when being tested, thesamples were kept under polyethylene to minimize evaporation.

Each pair of samples was then touched and felt in a blind box by twomembers of a panel of ten panelists and their impressions of surfacedryness were recorded according to a 04 grading scale wherein 0 means aparticular pair of samples exhibit equivalent surface dryness, 1 meansthat one of a pair of samples is to a low degree of confidence somewhatdryer than its opposite, 2 means that one pair of a pair of samples isto a high degree of confidence somewhat dryer than its opposite, 3 meansthat one of a pair of samples is considerably drier than its opposite,and 4 means that one of a pair of samples is much drier than itsopposite. Each pair of samples was only submitted to two panelists tosubstantially eliminate any effect of continued handling of the apparentsurface dryness.

V @The scores as outlined above were then statistically manipulated tominimize effects due to differences in human sensitivity and anytendency of panelists to be biased according to the order in which thesamples were touched or for other reasons. The result of the statisticalmanipulation was a group of overall scores for the four structureswherein the structure designated N (the structure subjected to patterndensification in accordance with the present invention) was taken as thestandard and given a score of O, i.e., the structure L (the uniformdensity pad) was scored relative to structure N. The score was expressedin the form of a yardstick which corresponds to the smallest significantdifference in grade. A net score difference of 1.0 yardsticks representsa difference which is statistically significant and a percent level ofconfidence. A difference less than 1.0 yardsticks indicates that nosignificant exists between samples up to 95 percent confidence level.The sample L achieved a net score of 2.5 yardsticks indicating that thesample N which had been subjected to the pattern densification of thepresent invention did, to a high degree of confidence exhibit a skindryness impression substantially higher than that of the uniform densityproduct sample L. A difference of 2.5 yardsticks indicates a clearlysignificant difference at the 95 percent level of confidence.

EXAMPLE 2 Unwet samples of the diaper structures referred to in Example1 were submitted to a similar panel of ten panelists and theirimpressions of softness were recorded according to the same O-4 gradingscale. The resultant scores were then statistically manipulated asdescribed in accordance with Example 1 and the not score yielded aresult of 2.5 yardsticks for the sample L (uniform density air-felt)relative the sample N (subjected to pattern densification) on the basisof softness impression indicating that the diaper structureincorporating the pattern densified air-felt of the present inventionexhibited a clearly significant difierence at the 95 percent level ofconfidence that the pattern densified structure exhibited asubstantially improved softness impression over the similar weight basisstructure of generally uniform density.

EXAMPLE 3 To substantiate that a substantial percentage of the area ofthe air-felt pad must be subjected to densification to providesignificant wicking, a series of sample diapers were prepared havingtufted air-felt pads subjected to varying percentages of densificationand tests were run, the object of which was to determine the amount ofmoisture retained at the point of liquid loading and at variousdistances therefrom. Sample 1 was a diaper having an air-felt pad thathad not been subjected to any pattern densification, i.e., 0 percentdensified. Sample 2 was a diaper prepared having an airfelt padsubjected to pattern densification extending over 30 percent of thearea. Sample 3 was a diaper prepared having an air-felt pad subjected topattern densification over 50 percent of the area. Sample 4 was a diaperhaving an air-felt pad subjected to pattern densifi cation over 70percent of the area and sample 5 was a diaper having an air-felt padwhich had been compressed or densified over the entire percent. For eachof samples 2, 3, and 4, the densification pattern was as generallyindicated in FIG. 1 of the drawing, in

each case utilizing 9/16 inch diameter undensified circular tufts andthe densification was done in a dry state.

Each of the pads then had added to it at its center a quantity of waterproviding for 3X loading thereof. By 3X loading is meant a quantity oftest liquid equal to three times the weight of the absorbent padstructure. This measured quantity of liquid was then poured onto thecenter of each diaper and approximately 30 minutes was allowed forabsorption and wicking thereof. At the end of the 30 minute period, thediapers were sectioned into a center strip 3 inches wide, i.e., bycutting l /2 inches to each side of the centerline and the remainder ofthe diaper was then sectioned into 2 inch wide strips. The liquidloading, i.e., weight of water per weight of cellulose for each stripwas then determined. To compensate for crosswise variations of thediaper, the values obtained on either side of the centerline at the samedistance were averaged. Results are tabulated below:

Liquid Loading (grams of liquid/grams of cellulose) At Varying Distancesfrom Ccnterline Sample No. Centerline at 2.5" at 4.5" at 6.75"

l 6.8 5.5 1.75 ().l 2 4.75 4.05 2.75 l.l I 4.8 4.1 2.9 0.75 4 4.7 4.252.95 l.l 5 5.15 4.4 2.9 0.75

EXAMPLE 4 To further define the lower limit of percentage area densifiedwhich would produce significant wicking, an additional series of testswas run, utilizing the same procedure set forth in Example 3 above,utilizing a pattern densification which, however, was not bilateral but,rather, comprised densification of the diaper pad along 5/16 inch widedensified transversely extending areas with the spacing between thedensified regions being varied to provide differing percentage areadensificatlOn.

Sample 1 was. again, completely undensified, i.e., percent. Sample 2 wasdensified over 10 percent of the area. sample 4 was densified over 30percent of the area, sample 5 was densified over 50 percent of the areaand sample 6 was completely densified, i.e., 100 percent densified.Results are tabulated below:

Sample l 6.8 5.5 l.75 Sample 2 6.55 4.6 L95 (1.7 Sample 3 5.3 4.75 2.5l.() Sample 4 5.35 4.7 2.7 0.7 Sample 5 5.0 4.4 3.0 1.0 Sample 6 5.l 4.42.9 .7

From the results tabulated, it is apparent that 10 percent densificationis not affected to produce substantial wicking from the central regionbut, above percent densified area, effective wicking occurs.

EXAMPLE 5 To substantiate that the softness impression was a function ofthe percentage area densified and to determine the effective limitsthereof, sample diapers were prepared having differing percentages ofarea densified surrounding undensified and generally circular regions orturfts of 9/ 16 inch diameter in the pattern shown and illustratedgenerally in FIG. 1 and submitted to expert panels for testing.Additionally, samples were prepared having straight line patterndensification as described above in Example 4 and also submitted forsoftness comparison to the expert panel. Sample 1 was completelyundensified. Sample 2 was densified in accordance with the pattern ofFIG. 1 with 30 percent densification. Sample 3 was pattern densified inthe pattern of FIG. 1 over 50 percent of the area. Sample 4 was fullydensified, i.e., over percent of the area. Sample 5 was patterndensified in the straight line pattern described above over 10 percentof the area. Sample 6 was pattern densified in the straight line patterndescribed above over 20 percent of the area. Sample 7 was patterndensified in the straight line pattern defined above over 50 percent ofthe area.

The samples were paired and presented in pairs to the panelists in blindboxes and the panelists assigned a softness score of 0-4 to each pairusing the criteria described in Example 1 above. Each sample wasassigned a separate score based upon the impression of the panelist. Forexample, if in comparing two samples a panelist decided that one samplewas, to a high degree of confidence somewhat softer than the othersample, the sample found softer would receive a score of +2 and theother sample a score of 2. All scores received by a sample were thenadded and divided by a factor equal to the product of the number ofpanelists times the number of samples to provide a comparative softnessgrade. Results are tabulated below, the higher softness gradeindicatedincreased softness impression.

Sample Softncss Grade From the results tabulated, it is apparent thatthe pattern densification of the general pattern shown and illustratedin FIG. 1 is substantially softer than straight line patterndensification of the same area and, in addition, that patterndensification in excess of approximately 50 percent results in only avery small change in softness impression. Further, pattern densificationof less than approximately 30 percent in the pattern shown illustratedin FIG. 1 has very small adverse affect on overall softness and thatover 50 percent there was already a significant decrease in overallsoftness approaching that of complete densification.

EXAMPLE 6 To substantiate that the improvement in surface drynessimpression noted at percentage area densifications less than 50 percentwere, in fact, valid indicators of objective surface dryness, a furthertest was run, the object of which was to determine the surface drynessof a diaper structure utilizing the pattern densified pads of thepresent invention, objective basis. A series of test pads werepreprepared of 4 inch by 4 inch size comprising a pattern densifiedair-felt padare disposed between a top sheet and back sheet as in adiaper structure. Sample 1 was a pad wherein the air-felt wasundensified, i.e., percent densified. Sample 2 was a pad having /16 inchwide linear densification over lO percent of the area. Sample 3 was apad having 5/16 inch wide linear densification over percent of the area.Sample 4 was a pad having 5/16 inchwide linear densification over 30percent of the area. Sample 5 was a tufted pad having 9/16 inch diameterundensified tufts and densified over 30 percent of thearea. Sample 6 wasa pad having 5/16 inch wide linear densification over 50 percent of thearea. Sample 7 was a tufted pad having 9/16 inch diameter undensifiedregions and densified over 50 percent of the area. Sample 8 was a tuftedpad having 1 1/16 inch diameter undensified tufts and densified over 50percent of the area. Sample 9 was densified over 100 percent of thearea.

Each of the samples was placed on a flat surface and a vtwo .inchdiameter flat bottomed cup having a plurality of spaced apart aperturesin the bottom was disposed on top of each sample. A measured quantity oftest liquid equal to three, times the weight of the pad was then addedto the cup and allowed to disperse into the pad through the aperturedbottom. After a wait of three minutes, two plies of previously weighedfilter 7 paper were placed on each sample and loaded with atwoinch/diameter weight applying a loading of 0.5 pounds per square inch tothe filter paper. After a wait of two minutes, the filter paper wasreweighed and the additional weight thereof due to absorbed liquid wasnoted. The increase in weights are tabulated below.

Sample No. Increase in Weight in Grams l l 4 L03 L53 The resultstabulated, it is apparent that increased densified area does result inimproved surface dryness; that a'tufted pattern is a notable improvementover a straight densified pattern and that over 50 percent densificationprovides only very small increases in surface dryness. The test furtherindicated that a 9/16 inch diameter tuft was substantially moreeffective in reducing surface dryness than a 1 1/16 inch diameter tuft.

that although an overall area densification range of approximately 20 tS O percent was acceptable, that preferably a pattern densificationwithin the range of 30 to percent was preferable. I 7

While the invention has been described, disclosed, illustrated and shownin termsv of an embodiment or modification which has assumed inpractice, the scope of the invention should not be deemed to be limitedby the precise embodiment or. modifications herein described, disclosed,illustrated. or shown, such other embodiments or modifications as may besuggested to those having the benefit of the teachings herein be intentto be reserved especially as their fall within in the scopeand spirit ofthe claims here appended.

. What is claimed is:

l. Absorbent pad structure combining high wicking and moisture transportcapability with high liquid absorptive capacity to provide high surfacedryness impression and high softness impression comprising, incombination,

an air laid pad of generally uniform weight basis consisting essentiallyof disintegrated cellulose pulp lap contained within a paper tissueenvelope defining therewith means for providing structural integritythereto, together with means for providing regions having high liquidabsorptive capacity spaced apart throughout the pad,

and

means for providing enhanced capillary wicking and thereby providinghigh liquid transport of absorbed moisture within the pad to portions ofthe pad remote from the point of moisture application, wherein i i I vsaid means for providing regions of high liquid absorptive capacitycomprises a bi-laterally staggered array of spaced apart generallycircular tufts formed by undensified regions of relatively low density,and

' said means for providing enhanced capillary wicking comprises abi-laterallyextending pattern of intersecting non-linear higher densityregions densified essentially only by-the application of selectivepressures thereto surrounding, separating and extending between each ofsaid low density tufts,

said non-linear densified high density regions comprising betweenapproximately twenty and fifty percent of the area of said pad tothereby enable said staggered array of spaced apart generallyundensified generally circular tufts and said bilaterally extendingpattern of intersecting nonlinear higher density regions together todefine means for providing both high dryness impression and highsoftness impression without substantial stiffening of the pad.

2. Diaper structure comprising an absorbent pad structure as defined inclaim 1 disposed between a urine permeable top sheet and a back sheet.

3. Absorbent pad structures defined in claim 1 wherein said higherdensity densified regions comprise between approximately thirty andforty percent of the area of said pad.

4. Absorbent pad structure defined in claim 1 wherein said patterndensification comprises compressed region formed by compression effectedsubheight and resilience above said higher density regions to loft saidhigher density regions away from surfaces in contact with said absorbentface and the pad resilience additionally extends said tufts a lesserdistance from the densified region on the reverse side of the pad.

5. Diaper structure comprising an absorbent pad structure defined inclaim 4 disposed between a urine permeable top sheet and a back sheet.

6. Absorbent pad structure defined in claim 4 wherein said nonlinearhigh density regions extend generally sinuously bilaterally across saidpad, and wherein said low density generally circular tufts are arrangedgenerally in a close packed hexagonal array and are of urine permeabletop sheet and a back sheet.

1. Absorbent pad structure combining high wicking and moisture transportcapability with high liquid absorptive capacity to provide high surfacedryness impression and high softness impression comprising, incombination, an air laid pad of generally uniform weight basisconsisting essentially of disintegrated cellulose pUlp lap containedwithin a paper tissue envelope defining therewith means for providingstructural integrity thereto, together with means for providing regionshaving high liquid absorptive capacity spaced apart throughout the pad,and means for providing enhanced capillary wicking and thereby providinghigh liquid transport of absorbed moisture within the pad to portions ofthe pad remote from the point of moisture application, wherein saidmeans for providing regions of high liquid absorptive capacity comprisesa bi-laterally staggered array of spaced apart generally circular tuftsformed by undensified regions of relatively low density, and said meansfor providing enhanced capillary wicking comprises a bi-laterallyextending pattern of intersecting non-linear higher density regionsdensified essentially only by the application of selective pressuresthereto surrounding, separating and extending between each of said lowdensity tufts, said non-linear densified high density regions comprisingbetween approximately twenty and fifty percent of the area of said padto thereby enable said staggered array of spaced apart generallyundensified generally circular tufts and said bilaterally extendingpattern of intersecting non-linear higher density regions together todefine means for providing both high dryness impression and highsoftness impression without substantial stiffening of the pad.
 2. Diaperstructure comprising an absorbent pad structure as defined in claim 1disposed between a urine permeable top sheet and a back sheet. 3.Absorbent pad structures defined in claim 1 wherein said higher densitydensified regions comprise between approximately thirty and fortypercent of the area of said pad.
 4. Absorbent pad structure defined inclaim 1 wherein said pattern densification comprises compressed regionformed by compression effected substantially from an absorbent face ofsaid pad structure so that a residual density gradient exists normallythrough said pad and said tufts extend with substantial height andresilience above said higher density regions to loft said higher densityregions away from surfaces in contact with said absorbent face and thepad resilience additionally extends said tufts a lesser distance fromthe densified region on the reverse side of the pad.
 5. Diaper structurecomprising an absorbent pad structure defined in claim 4 disposedbetween a urine permeable top sheet and a back sheet.
 6. Absorbent padstructure defined in claim 4 wherein said nonlinear high density regionsextend generally sinuously bilaterally across said pad, and wherein saidlow density generally circular tufts are arranged generally in a closepacked hexagonal array and are of generally uniform diameters of betweenapproximately three-eighths and three-quarters of an inch.
 7. Diaperstructure comprising an absorbent pad structure defined in claim 6,disposed between a urine permeable top sheet and a back sheet. 8.Absorbent pad structures defined in claim 6 having an average density ofapproximately 0.14 grams per cubic centimeter and wherein said circularregions are approximately 9/16 inch diameter.
 9. Diaper structurecomprising an absorbent pad structure as defined in claim 8 disposedbetween a urine permeable top sheet and a back sheet.